Despite almost three decades of attention to the problem of adolescent smoking, relatively little attention has been paid to addressing the question of how adolescents progress from experimentation to subsequent stages of use, and what predicts transitions up or down at each level. The overall goal of this program project is to increase our understanding of the patterns of adolescent smoking. Our hope is to track the natural history of these patterns and to examine in-depth some key, selected contextual factors that may influence them. Our focus is on the social-emotional contexts with an emphasis on depression, anxiety, problem behaviors, and positive affective domains. As a program project, we will examine the intersections of these social and emotional domains. The cornerstone of this program project is the establishment and maintenance of a high-quality cohort of adolescents. Our design in establishing this cohort draws on elements of both epidemiology and developmental psychology, and may be thought of as an "accelerated developmental trajectory of smoking." We will develop our sample in a planned way, maximizing our ability to study movement across levels or stages of smoking. Our program project comprises three research projects and three cores. The three research projects are: 1) Proximal Contexts of Adolescent Smoking Patterns (Robin Mermelstein, P.I.); 2) Developmental influences on Adolescent Smoking Patterns (Lauren Wakschlag, P.I.); and 3) Smoking's Effect on Emotion in Adolescent Smokers (Jon Kassel, P.I.). All three projects utilize a common core cohort to test broad-based hypotheses, and in addition, each project utilizes a state-of-the-art, in-depth measurement modality to examine intensively key constructs on a sub-sample of the cohort. Across the projects, we will use a combination of ecological momentary assessments through the use of hand-held computers (Project 0001), family observations of parent-adolescent discussions and interactions (Project 0008), and psychophysiological reactions of adolescents to smoking in controlled laboratory settings (Project 0003). State-of-the-art analytic techniques will explore the intersections of these variables. We will have three cores. The cores allow us to develop a series of integrated, cross-project analyses and papers that address how combinations of variables across projects (e.g., family, peer, situational/contextual, emotional) conjoin with each other in producing the patterns of adolescent smoking from experimentation onward. These cores will support the basic functions of the program project, including the establishment and maintenance of the cohort. The three cores are: A) Scientific/Administrative Core (Robin Mermelstein, Director); B) Recruitment and Retention Core (Susan Curry, Director); and C) Data Management, Measurement, and Statistics Core (Donald Hedeker, Director).